A short answer is the natural way to answer a polar question (also known as a "yes/no question"), that is, a question which invites a simple yes/no answer.
Polar questions begin with an auxiliary verb or modal verb and are usually, but not always, answered with the same auxiliary/modal verb. We use ellipsis to avoid having to repeat the rest of the words in the question.
|Verb||Verb conjugation||Tense||Pronouns||Example yes response||Example uncontracted no response||Example contracted no response(s)||Notes|
|be||am||present||I||Yes, I am||No, I am not||No, I'm not|
|are||present||you, we, they||Yes, you are||No, you are not||No, you're not / No, you aren't|
|is||present||he, she, it, one||Yes, it is||No, it is not||No, it isn't / No it's not|
|was||past||I, he, she, it, one||Yes, I was||No, I was not||No, I wasn't|
|were||past||you, we, they||Yes, you were||No, you were not||No you weren't|
|do||do||present||I, you, we, they||Yes, I do.||No, I do not.||No, I don't.|
|does||present||he, she, it, one||Yes, it does.||No, it does not.||No, it doesn't.|
|did||past||All||Yes, I did.||No, I did not.||No, I didn't.|
|have||have||present||I, you, we, they||Yes, I have.||No, I have not.||No I haven't.|
|has||present||he, she, it||Yes, it has.||No, it has not.||No, it hasn't.|
|had||past||All||Yes, I had||No, I had not.||No, I hadn't.|
|can||can||present||All||Yes, I can.||No, I cannot||No, I can't|
|could||past||All||Yes, I could||No, I could not.||No, I couldn't|
|will||will||present||All||Yes, I will.||No, I will not.||No, I won't|
|would||past||All||Yes, I would||No, I would not.||No, I wouldn't.|
|may||may||present||All||Yes, I may.||No, I may not.||?No, I mayn't.||"Mayn't" is rare|
|might||past||All||Yes, I might.||No, I might not.||No, I mightn't.|
|must||must||present||All||Yes, I must.||No, I must not.||No, I mustn't.|
|shall||shall||present||All||Yes, I shall.||No, I shall not.||No, I shan't.|
|should||past||All||Yes, I should.||No, I should not.||No, I shouldn't.|
|ought to||ought to||present||All||Yes, I ought to.||No, I ought not to.||No, I oughtn't to.|
|dare||dare||present||All||Yes, I dare.||No, I dare not.||No, I daren't.|
|need||need||present||All||Yes, I need.||No, I need not.||No, I needn't.|
It is important that students learn to include the modal verb after "yes" or "no" as answering with a simple "yes" or "no" will be taken by a native speaker to indicate that the speaker is either being rude or has no interest in the conversation and the conversation will end abruptly, with both parties possibly feeling mildly offended. Obviously the speaker can omit the "I do" part if (s)he then goes on to say something else immediately afterwards:
- Does she speak English? - No, but she's started taking lessons.
Students should also take care to repeat the modal or auxiliary and not the verb. In other words, the answer to the question Do you like chocolate? is Yes, I do. (*). (The longer, more complex, answer to this is that it's OK to say "Yes, I verb" only if the verb is used intransitively. Thus, e.g. we can ask "Do you dance?" and respond either "Yes, I do" or "Yes, I dance". The problem is that like is a transitive verb which cannot be used intransitively and therefore needs an object, so *"Yes, I like" is ungrammatical but "Yes, I like it/that" is grammatical. Don't try to explain this though, just correct them to "Yes, I do".)
Not all questions beginning with Did/Are you...? etc. lead to a simple yes/no answer. One way of getting students to respond more fully is by asking "either/or" questions, for instance, Did you..., or were you..?
Depending on context, some polar questions, such as Would you like a cup of tea?, require a totally different response, i.e. Yes, please./No, thanks.